In the vast ocean, all creatures are vulnerable. Bottlenose dolphins are cetaceans that rarely become prey, thanks to their size, their intelligence, the use of echolocation and their level of socialization that gives them a significant advantage by staying in groups and intimidating their opponent. However, two predators will take the smallest opportunities to feed on dolphins: killer whales and sharks.

We know that the killer whales are expert hunters, especially when they hunt in organized groups. Although there are few documented cases, these animals that are the world’s largest dolphins, attack other species of smaller dolphins, mainly young, newborn or sick. To do it they separate the mother from the calf, making impossible to the latter defend its offspring.

However, a group of orcas does not feel intimidated by a large pod of dolphins. Although there are no records of this kind of attack to bottlenose dolphins, there are videos where a pod of killer whales approaches aggressively to groups of dolphins of other species, and as if they were seals, they beat them and throw them into the air until they are stunned and finally feed on them. Several types of dolphins suffer this kind of aggression, and the bottlenose dolphins are likely part of this list.

Regarding sharks, the most dangerous species for members of the genus Tursiops are the largest: tiger shark, sand shark, bull shark and, of course, the great white shark. It is not uncommon to observe dolphins with scars from shark attacks, which means they are not easy prey and their escape techniques often help them survive.

A study conducted in Shark Bay, Western Australia, revealed that 95 of 128 bottlenose dolphins analyzed showed scars from shark bites, mostly from tiger sharks. The frequency of new body marks and the high attack rates suggest that bottlenose dolphins are at risk in this locality more than in other parts of the world.

A few cases with rays are known. Although they are not dolphin predators because they have a diet based on small fish, mollusks, and plankton, the trauma and infections they cause with the sharp edges of their tail sometimes become deadly.

Commercial fishing can be a risky business, but not when you have the right members on your team! In some locations, fishermen are getting help from self-trained Bottlenose Dolphins! This is a winning outcome for the dolphins as well as for the fishermen that are reaping such rewards. What is really interesting in this study in Brazil is that the dolphins were never formally trained for such an outcome.

What has occurred is that the dolphins are successful with getting the fish into a central location. Then they send out signals to the fishermen that inform them where they should drop their nets to catch the fish. It is very evident the social and cooperation skills of these dolphins are extremely well developed.

Additional research on these dolphins also shows they are extremely social and cooperative within the group. This is based on information that has been published in the Royal Society Biology Letters if you are interested in finding out more. It is believed that these factors help to explain why some of the dolphins in the wild do help humans and other don’t take part in it.

The behaviors are well synchronized and fishermen have been able to rely on those signals. They often include tail or head slaps in the water in given locations. The fishermen are able to quickly put their nets in the right place. This allows them to get the fish instead of guessing where to put the nets and hoping for the best. Such information has been observed and documented by Fabio Daura-Jorge of the Federal University of Santa Catarina.

Along with several colleagues, he has been able to see the outcome of such experiences. So what is in it for the dolphins? They get to dine on the fish that find their way out of the nets. They are patient and wait for that moment to arrive. Such observations were noted by Daura-Jorge and his team through boating surveys that took place over the course of a 2 year period.

They used photos to identify the dolphins. This allowed them to classify the groups as cooperative or non-cooperative based on their interactions or lack of interactions with the fishermen. The use of computer modeling allowed for the social relationships among the dolphins to be successfully identified.

What was found is that those dolphins that were cooperative spent far more time with each other, even when they weren’t participating in activities that helped the fishermen. It is believed that there are many factors at work here that determine if a relationship will occur naturally between humans and dolphins. They include genetics, social learning, and ecology. 

It is believed that information transferred from one generation of the dolphins to the next is very important here. The older dolphins teach the younger ones to be able to successfully help the fishermen. There have been numerous documentations about such behaviors within groups of dolphins in various areas. One that is widely discussed is the process of sponging by the dolphins in Shark Bay, Australia. If you aren’t familiar with sponging, it is the process of these Bottlenose Dolphins tearing pieces of sponges and covering their snout with them while they forage for food. This protects them from damages to that part of the body. 

There are plenty of unique behaviors identified within dolphin groups, and their intelligence level is believed to be a big part of them. According to Lori Marino from Emory University, the size of the dolphin’s brain should be used to help measure their intelligence. She and many others believe the dolphin ranks #2 – right being humans.

Source: http://news.discovery.com/animals/helpful-dolphins-120502.html

– Dolphins are dying more frequently than ever before because of the consequence of human activities. Among them:

– They get caught in fishing net quite often. Usually, fishers are not targeting dolphins, but commercial species which are also the prey of dolphins. Gillnets, trawls, and longlines are some of the most dangerous fishing devices that trap and kill dolphins.

– Dolphins also die frequently because of the ocean pollution, either by poisoning or by eating drifting garbage.

– Other times these cetaceans die as result of beach strandings which some think are caused by noise pollution.

– Finally, some industries intentionally kill dolphins for commercial purposes. While protected in most parts of the world, some countries invoke their ancestral customs to kill an insulting number of dolphins every year.